Amplifying stethoscope



March 24, 1936. J. WEINSTEIN 2,035,034

AMPLIFYING STETHOSCOPE Filed Feb. 2, 1935 Ema/whoa; Joseph 14 641252e-Ln Patented Mar. 24, 1936 UNITED STATES PATENT OFFICE AMPLIFYINGSTETHOSCOPE Joseph We'instein, Brooklyn, 'N. Y.

Application February 2, 1935, Serial No. 4,697

1 Claim. (01. 179171) This invention relates to electricallyamplifynected by conductors 32 and 33 with the respecing stethoscopessuch as are shown in my prior tive conductors 28 and 30, the resistance29 and Patent No. 1,976,707 of October 9, 1934 and more condenser 3|being thus connected in parallel beespecially relates to improvements inthe circuits tween the cathode 25 and ground l8.

5 and arrangements of parts shown and described A conductor 34 connectsthe plate 24 with one in the aforesaid patent end of a choke coil 35having its other end conone important object of th i v nti i t nected bya conductor 36 with a ground 31 through improve the sensitivity ofdevices of this char a condenser 38. The choke coil has a groundedacter. core '39 and forms what is termed an audio choke.

A second important object of the invention is A l megohm resistanceWinding s O e end 10 to provide, in such a device, a simple andeflicient Connected to the COIldllCtOl 34 y a uctor 4| volume controlfor uch stethoscopes and its other end connected to the COIldllCtOl 36,

A third important object of the invention is to between the condenser 38and Coil by a conprovide a separate choke 11 for t utput of ductor 42.The audio chock 35 and resistance 15 Such instruments. 40 are thusconnected in parallel between the 15 A fourth important object of theinvention is plate 24 and ground t provide an improved amplifyingStethoscope Movable over the windings of the resistance 40 whereinamplification will be effected without the is a Contact 43 Which isConnected by a conductor use of a tra fo m 44 with a 0.2 microfaradcondenser 45. At 46 is With the above and other objects in view, theavacuum tubehaving grid ap 8 e de 20 invention consists in general ofcertain novel by a pail of parallel connected grids a a hode circuitarrangements and combinations of details 50 carrying a fourth grid- 5|anda heater fi ament hereinafter n described and claimed, one 52. Thecondenser 45 is connected by a conductor bodiment of the circuits andapparatus used be- 53 with the grid The Conductor 53 0011- ingillustrated in the accompanying drawing, nected by a'conductor 54with'one end a 500 25 wherein: megohm resistance 55 having its other endcon- The figure is a Wiring diagram of the Complete nected by aconductor 56 with a ground 57. device The cathode 50 is connected by aconductor 58 In the embodiment of the invention shown in with a 5 megohmresistance 59 having its other the accompanying drawing there isprovided a end connected by a conductor 60 to the ground combinedstethoscopic sound receiver and micro- Wire A l microfarad Condenser isphcne or microphonic Stethoscope m from which nected by a conductor 62with the conductor 58 leads a cable H of the usual two wire type, oneand conductor 63 with the ground wire wire being connected to a contactl2 and the other the reslstance 55 and Condenser being thus Wire beingconnected to a Contact W A Shield connected in parallel between thecathode and 35 I4 surrounds at least a portion of the cable adjaground Tgrids 49 are connected by cent the contacts, the latter being supportedby ductor 64 h Source 65 of 221/2 volt current Said Shield A jack havingSpring contacts '5 and a 0.5 microfarad condenser 66 is bridged and I5is provided to receive the contacts l2 and across between t Conductors52 and 40 I3 so that they engage respectively with the said The plate.4815 connected by a conductor 61 4O jack Contact? A conductor leads fromthe and a 0.5 ml'crofarad condenser 68. A conductor contact I5 to aground I8 and a conductor l9 leads 69 the cpndtlctor 67 with one end ofa from the contact [6 through a 1 megohm resistchoke C011 havlpg Itsother end connected by ance 20 and is connected to the ground wire H.qonducmr H Wlth one end of a 20 megohm Also a conductor 2 I 18 a C15from the Contact '6 to resistance 72. The other end of the resistance 1245 the g 22 of a Vacuum tube 23 which also Com is connected by aconductor 13 to the conductor tains a plate 24, a cathode 25 and aheater fila- 36 between condenser 38 and c011 35 $0 that ment 26. Theconductor 2| is preferably covered the 0011 m 15 grounded through the-reS1stan-ce r b h M 21 12 and condenser 38. The choke 0011 has its as ya s 1e core 14 grounded and forms an audio ch ke f F The cathode 25 isconnected by a conductor 28 t t 45 O or )0 with one terminal of a 10megohm resistance 29 At is a third vacuum tube having a grid which inturn has its remaining terminal con- 16, plate 77, cathode I8 and heaterfilament l9. nected through a conductor 30 with the ground A conductorconnects the condenser 68 with ()0 Wire 11. A 1 microfarad condenser 3|is conthe grid 16 and t s nduc s n t d by 55 a conductor 8! with one endof a 500 megohm resistance 82 having its other end grounded through aconductor 83. The cathode 18 is connected by a conductor 84 with one endof a 2 megohm resistance 85 having its other end connected by aconductor 86 with the ground wire 83. A 1 microfarad condenser 81 isconnected. by a conductor 88 with the conductor 84 and by a conductor 89with the conductor 86 so that the resistance 85 and condenser 81 areconnected in parallel between the cathode l8 and the ground. The plate71 is connected by a conductor 96 with a 0.5 microfarad condenser 9|,this condenser being connected by a conductor 92 with an output terminal93. The other output terminal 94 is connected by a conductor 95 with theconductor 88. A 30 Henry choke coil 96 has one end connected to theconductor 90 by a conductor 97 and its other end connected by aconductor 98 to the positive terminal 99 of a connection for voltcurrent. The negative terminal for this current is grounded through aconductor Ifll.

Six volt heater terminals I02 are connected by conductors l3 to theheater filaments of the several tubes so that such filaments areconnected in multiple.

In use, the microphonic stethoscope is applied to a portion of theanatomy over the organ to be auscultated, one or more sets of telephoneear pieces having been connected to the cut put terminals. Then thesound impulses emanating from the organ are translated into electricalimpulses through the action of the microphone, amplified by theamplifier, and received through the ear pieces as amplified sounds.Obviously a loud speaker device may be connected to the out-putterminals if desired and, when arranged in this manner, the apparatusmay be used for clinical demonstrations.

It will be observed that adjustment of the contact 43 along theresistance 40 controls the input to the grid of the second tube andthereby controls the volume delivered to the output terminals of thedevice. By this means faint sounds may be amplified to clearness whileloud sounds may have their amplification restricted so as not to beunpleasant to the auditor.

There has thus been provided a simple and efficient device of the kinddescribed and for the purpose specified.

It is obvious that changes may be made in the arrangement of the partswithout departing from the spirit of the invention. It is not,therefore, desired to confine the invention to the exact arrangementhere shown, but it is desired to include all such as come within thescope of the appended claim.

What is claimed is:-

An amplifying instrument for microphonic stethoscope circuits comprisingin-put terminals, a set of three electronic vacuum tubes each having agrid, a plate, a cathode and a heater element, the middle tube of saidset further having a pair of grids between which the plate of said tubeis located, a conductive connection between one of said terminals andthe grid of the first tube, a ground connection from the other terminal,a resistance bridged between said terminals, a conductive connectionhaving a resistance therein and connecting the cathode of the first tubeto the ground, a condenser bridged between the terminals of the lastresistance, a choke coil and a third resistance conductively connectedin multiple to the plate of the first tube and connected to the groundthrough a second condenser, a connection from the grid of the secondtube to the third resistance through a condenser and arranged forvariable connection to said third resistance, a resistance providingground connected to the last connection between the grid and condenserof said last connection, a resistance providing ground for the cathodeof the second tube and having a condenser bridged around the resistancetherein, a conductive power input connection for said pair of grids, acondenser bridged between said power input connection and the groundfrom the second cathode, a connection between the plate of the secondtube and the grid of the third tube, a choke coil having one terminalconductively connected to the plate of the second tube and its otherterminal connected conductively to the second condenser through aresistance, a conductive ground connection for the grid of the thirdtube including a resistance, a conductive ground connection for thecathode of the third tube and having a condenser bridged around itsresistance, an output terminal conductively connected to the lastconnection between the cathode and its grounding resistance, a secondout-put terminal, a connection between the plate of the third tube andthe second output terminal, a choke coil having one end conductivelyconnected to the last plate and its other end conductively connected tothe corresponding end of the second choke coil, a power in-put con.-nection supplying current to said plates through said choke coils, and aheater circuit for said heaters.

JOSEPH WEINSTEIN.

